1. Field of the Invention
Anti-backlash gear assemblies or devices.
2. Description of the Prior Art
A preliminary search directed to the novel features of the present invention uncovered the following prior art U.S. Pat. Nos.: 2,081,644 to Smythe; 2,640,428 to Houghton; 2,896,466 to Wiseman; 2,918,826 to Miller; 3,020,775 to Musser; 3,166,952 to Lang; 3,359,819 to Veillette et al. ; and 3,365,973 to Henden.
Among these patents, several are directed to arrangements where the two parts of a split gear are actuated for anti-backlash collective tooth expansion by action of a spring means that is constantly effective; the Henden and Veillette et al patents. Such constant effectiveness of the spring means affords automatic effectuation of the anti-backlash action, but the spring action causes the teeth of the split gear to exert a constant bias force against the teeth of the gear or pinion with which the split gear is mated. Under some circumstances, such constant anti-backlash force can lead to undue wear of the gear teeth.
One patent, the Miller patent, employs a mechanical adjusting means for a split-gear type of anti-backlash control. While this tends to eliminate the constant bias force of the spring actuation type above, it does require periodic manual adjustment, which may be inconvenient if not impossible under some operational circumstances.
Several patents, the Smythe, Houghton, and Wiseman patents, employ hydraulic pressure means for spreading the teeth of the split gear into clearance-free contact with the teeth of the mating gear. In both arrangements the split-gear tooth-spreading-force is generated and maintained during anti-backlash action by the hydraulic pressure from an external source supplied to a piston means. This tends to create the same wear-inducing mating-tooth-engaging forces created by the spring bias force discussed above in connection with the Henden and Veillette et al. patent disclosures.
The Miller and Lang patents disclose anti-backlash gear drive constructions of relatively complex nature that are even more impertinent to the features of the present invention than those of the preceding patents discussed above.